Autocorrelation Function.

Dear All
I hope everyone is fine. I had a rectangular space. In divided it into x and y cells. Then I collected data (temperature) for every cell at equal time intervals and performed density averagaing for all the space. Thus I have overall average value of a variable for whole space now. I wish to perform statistical analysis. Searching google suggests AUTOCORRELATION of the collected data. I am unaware of the following.
1. AUTOCORRELATION FUNCTION
2. EULER'S & LAGRANGE'S AUTOCORRELATION FUNCTIONS (my case is euler)
3. Anything else related to above 2 points.
I need help. Can anyone suggest me any simple literature for the said problem explicitely giving definitions, concepts and mathematical equations for computer implementation?
Thanks to all.

Dear All
I hope everyone is fine. I had a rectangular space. In divided it into x and y cells. Then I collected data (temperature) for every cell at equal time intervals and performed density averagaing for all the space. Thus I have overall average value of a variable for whole space now. I wish to perform statistical analysis.

Why do you want to "perform statistical analysis"? What questions do you want the analysis to answer (I know this will make me unpopular, but that is the question you should have asked yourself before designing the expeiment)?